Spark plug



Oct. 16, 1923. 1,471,283

J. A. ROGERS SPARK PLUG Fiied' Jan. 5, 1922 1 l9 7 I /0 3 l fnvenziof,

' seph Y/Pqgers.

Patented on. 16, 1923.

UNITED STATES JOSEPH A. ROGERS,

OF RUMNEY DEPOT, NEW HAMPSHIRE.

SPARK PLUG.

Application filed January 5, 1922. Serial No. 527,114.

To all whom it may concern.

Be it known that I, JOSEPH citizen of the United States, residing at Rumney Depot, in the county of "Grafton and State of New Hampshire, have invented certain new and useful Improvements in Spark Plugs, of which the following is a specification.

The object of my invention is to provide a spark plug which, while it is efiiciently insulated, will not foul or become oil soaked; will not crack or break under heavy duty, and. which will not be cracked or broken by mechanics while being attached to the motor. Another object of my invention is to construct a spark plug in a manner that such carbon as adheres to it may be quickly and easily removed.

The-detailed construction of my improved spark plug will be more clearly understood by referring to the accompanying specifica lion and drawing, in which Fig. 1 represents an assembly of my improved plug in Fig. 2 represents abot-1 sectional elevation; tom plan view thereof, and Fig. 3 represents a section on the line 33, Fig.1.

Referring moreparticularly to Fig. 1, 1 represents the usual body of the plug, of

steel, having the usual screw-thread 2 for insertion into the engine cylinder head. A refractory insulator 3, preferably made of fused quartz, is inserted into the chamber 4 from the screw-threaded end of the plug. Mica washers 5, 6 and a short mica tube 7 may be employed if desired as cushioning means to separate the quartz block from the steel walls of the chamber 4-. While the mica in this case also is an insulator, of course, the quartz is a sufficient insulator of itself, so that the function of the mica here is more as a shock-absorber, preventing the refractory glass or quartz insulator 8 from being broken. The main body of the plug 1 is also chambered to receive a conical elec trode holder 8, also of steel, which is in sulated from the main body portion 1 by means of a mica cone 9, madeby winding thin mica sheets, about 1 5-" X 3", each sheet overlapping, held together by Japanese tissue under pressure, and wound on a mandrel of similar form to electrode holder 8. The mica cone in this case is used as an insulator for insulating the electrode holder 8 from the main body 1 of the plug. The refractory block or bushing 3 of glass or fused quarts is provided with a hole through A. Roonns, a,

its center for the reception of the positive electrode 10 of nickel which has a screwthreaded end 11 by means of which this electrode is screwed into the electrode holder 8, the latter being suitably chambered and threaded for receiving it. The holder 8 has a central core or wire of copper 12 which extends the length of the holder 8, into the end of the negative electrodelO at one end and at its top end has a copper cap or disc 12 attached thereto. The purpose of this copper core and disc is to. ensure good electrical conduction from the positive electrode 10 to the top terminal 13 which will be referred to later. This copper core of the ceniral electrode gives'a spark of greater volume than with a steel core. Around the positive electrode holder 8, and on top of the main steel body portion 1 of the plug,

is a second refractory insulating bushing 14 of quartz, or this insulation may be accomplished by using mica discs in place of the quartz if desired. The top part of the electrode holder or member 8 is screwthreaded and by means of a copper washer 15 and a hexagonal brass nut 16 screwed onto the member 8 the quartz insulator or mica insulators 14: are held in place, above which may also be screwed on (in intimate contact with the copper disc 12') the brass terminal 13.

The bore of the plug at'the bottom or chamber l is screw-threaded to receive a screw-plug or disc 17 having a hexagonal head portion 17 so as to enable the plug to be screwed in and out by means of a wrench or pliers. The purpose of this plug is to keep the quartz insulating bushing 3 in place. 18 represents the negative electrode which is fastened into the plug 17 by drilling the latter for its reception, and subsequcntly prick-punching in place. The retaining disc or nipple 17 may be from is to in depth.

. In assembling my improved spark plug, the conical member 8 with the insulating mica cone 9 slipped thereon is first dropped into place by inverting the plug, then the mica tube '2, subsequently the mica washers 5, followed by the insertion of the quartz insulating bushing 3. The positive electrode 10 is now inserted through the hole in the bushing 3 and screwed into place in the member 8. The lower set of mica washers 6 are now dropped into place over the electrode 10 and bushing 3. The retaining nip ple Or screw-plug 17 is theflscrewed in, and then the negative electrode 18 is inserted in the latter with a driving fit and pick-punched in as hereinabove described, The copper core and disc 12 and 12 respectively are dropped in, and over the member 8 and mica cone 9, the insulator 14, Washer 15, nut 16 and brass terminal 13 respectively are assembled. An asbestos filled copper gasket 19 may be provided for making the usual tight joint at the cylinder head. The main body portion of the plug may be provided with radiating ribs a and b.

In accordance With the provisions of the patent statutes, I have described the principle of operation of my invention, together with the device which I now consider to represent the best embodiment thereof, but

I desire to have it understood that the device shown is only illustrative and that the invention may be carried out by other means. What I claim as new and desire to secure by Letters Patent of the United States is:

1. A spark plug comprising a main body portion having the usual screw-threaded end, a removable central core insulated from the main body portion, an electrical conductor of better conductivity than steel extending through said central member, a negative electrode carried by the main body portion. a fused quartz bushingbeneath the removabe central member, means for retaining the fusedquartz bushing in place in the main body portion, and a positive electrode extending through the bushing and connected to the end of the conductor in the removable central member.

2. A spark plug comprising a main body portion having the usual screw-threaded end, a removable central member of frustum shape, a frustum-shaped insulating body between said central member and the main body portion, a chamber in the main body portion beneath the removable central memher, an insulating bushing in said chamber, a positive electrode extending through said bushing, and a conductor extending through the frustum-shaped removab'e central member and connected at its lower end to the positive electrode.

3. A spark plug comprising a main body portion having the usual screw-threaded end, a removable central member of frustum shape, a frustum shaped insulating body be tween said central member and the main body portion, .a chamber in the main body portion beneath the removable central mem-- her, an insulating bushing in said chamber, a positive electrode extending through said bushing and a conductor having a T-shaped head extending through the frustum-shaped removable central member and connected at its lower-end to the positive electrode. JOSEPH A. ROGERS. 

